Call blockages force the local switch to make more attempts before an off-hook telephone obtains a dial tone. On a switch with too many blockages, an off-hook telephone may not receive a dial tone at all. A previously known method of determining call and line blockages relied on probability not facts. This previous method used telephone traffic measurement studies, such as those available from TRAFFIC 30 reports, which were based on 30 minute reports. Each report would only provide the one hundred call seconds (CCS) method which measures of telephone traffic load obtained by multiplying the number of calls in an hours by the average holding time per call in seconds & dividing the product by 100. Using this type of report, the maximum possible CCS that can be handled by 1 circuit in 1 hour is 36. However, the CCS is a usage statistic, it is not a measure of whether or not a line is involved in a call a blockage. By operation of the theory that the most busy line is most likely to cause the most call blockages, the busiest line or lines were moved to other trunk groups or other switching modules to alleviate blockages. Typically, to get meaningful information, TRAFFIC 30 reports for days even months are gathered for statistical analysis. But even then, not all of the lines experiencing blockages will be found because of the imprecision of statistical techniques. Further, often by the time the sample data has been accumulated, calling patterns and blocking patterns have changed, leaving the data stale and the actions taken on the data potentially ineffective.
It is an object of the present invention to provide a method and apparatus to determine blockage of actual lines from data, not just statistical probabilities.
It is another object of the invention to provide a method and apparatus that can locate actual blockages in a few hours instead of the many days that were previously required to get a probable answer.